Advanced modeling of thermal screens: Maximizing energy and water savings in greenhouses

Abstract

Maintaining an appropriate greenhouse microclimate for optimal plant growth often incurs significant energy costs due to heating and cooling demands. This study investigates the potential of thermal screens to minimize energy and water consumption in greenhouses. A detailed hourly thermal model was developed to simulate the thermal behavior of greenhouse components, incorporating all relevant heat transfer mechanisms. The model uniquely considers the presence of plants and their evapotranspiration processes, a crucial factor impacting energy and water usage within greenhouses. The model assessed the impact of six thermal screen materials on both heating and cooling loads, water consumption, and solar radiation transmission. Results revealed that implementing thermal screens leads to a substantial 41 % reduction in annual heating demand compared to greenhouses without screens. The impact on cooling loads varies significantly by screen type, ranging from an unfavorable 73 % increase to a beneficial 24.5 % reduction compared to conditions without screens. The white polyester screen achieved the best overall energy performance, reducing annual energy demand by 33.4 %. Additionally, the PH-66 (al) screen showed the highest water-saving potential, decreasing annual water consumption by 47 %. Moreover, the PH-super thermal screen enabled the highest solar radiation transmission to the plants. These findings suggest thermal screens as a promising strategy to enhance greenhouses' sustainability and economic viability, particularly in regions experiencing distinct winter and summer seasons.